None.
1. Field of the Invention
The present invention generally relates to an airfoil with a variable or adjustable lift surface. Specifically, the invention is a wing having one or more telescoping segments deployed via an actuator composed of a material responsive to heat supplied by a fluid or electrically.
2. Background
A telescopic or variable area wing is a device having one or more segments of progressively smaller cross section. It is widely known that such devices improve aerodynamic performance and reduce the total volume required for wing stowage.
The related arts include a variety of telescopic wing geometries and deployment mechanisms. Several noteworthy inventions are reviewed below.
Sarh, U.S. Pat. No. 4,824,053, describes and claims a telescopic airfoil with tubular spars. Spars are threaded and telescoping when rotated so as to move in a linear fashion thereby extending and retracting wing segments.
Gerhardt, U.S. Pat. No. 4,181,277, describes and claims a movable wing externally mounted to slide along the trailing edge of a stationary wing. The wing segment is extended and retracted by a single screw jack with traveling nut mounted to the structure on the fuselage centerline above the wing. Screw jack is operated by a hydraulic motor powered by a source of hydraulic fluid driving through a common gearbox.
Gioia et al., U.S. Pat. No. 3,672,608, describes and claims a hydraulic mechanism for supporting a telescopically mounted wing section of an extendible aircraft wing. Hydraulic cylinders, fixedly attached to a telescopic wing section, are in slidable or rolling contact with the other wing section via pistons. The inner wing section is extended from the outer wing section by means of a pair of screw jacks.
Kapenkin, U.S. Pat. No. 2,858,091, describes and claims a retractable wing having a pair of motor driven threaded rods. Threaded rods engage threaded bushings at one end of each of the retractable wings.
Enmi, U.S. Pat. No. 2,743,072, describes and claims a collapsible wing system for aircraft. Wing segments are extended and retracted via a hydraulic means comprising an end closed cylinder and a series of telescopic sleeves each having an external diameter similar to the internal diameter of its adjacent inboard sleeve. Each telescopic sleeve is joined to a wing segment so as to couple sleeve movement to wing segment movement.
Makhonine, U.S. Pat. No. 2,550,278, describes and claims a variable surface wing having an inner wing segment with four spars fixed lengthwise along the wing. Movement of the spars and wing segment attached thereto is achieved via guiding rollers.
Murray, U.S. Pat. No. 2,487,465, describes and claims a variable area wing having an I-beam along its length wherein rollers allow sliding motion between wing segments. A hydraulically or electrically operated device is used to effect motion between segments.
Gibson, U.S. Pat. No. 2,423,095, describes and claims a variable area wing having a mechanically driven telescoping shaft within the wing segments. Wing segments are deployed and retracted via the telescoping shaft.
Kraaymes, U.S. Pat. No. 2,420,433, describes and claims a variable area wing having panels extended or retracted via screws, worm, chain, hydraulic piston, or gear segments and spurs. Power for retracting and extending the wings may be supplied manually, electrically, hydraulically, or by engine power.
Koch, U.S. Pat. No. 2,344,044, describes and claims an aircraft wing having stringers with rollers parallel to spars within the wing. Rollers act as bearings and guides for the movable wing extensions.
Fitzurka, U.S. Pat. No. 2,249,729, describes and claims a retractable wing tip having a pair of hydraulic reversing jacks in a paired arrangement attached to the wing tip via stems. Stems communicate movement from the hydraulic reversing jacks to the wing tips.
The referenced inventions rely upon coupled movement between mechanical elements within a control system powered by various means. Such inventions are heavy, complex, susceptible to mechanical failure, lack backup operability, and require a dedicated power source.
Shape memory alloys, also referred to as SMAs, are two-phase materials activated either thermally or electrically. SMAs, one example being. Nickel-Titanium, exhibit a phase transformation in crystal structure when cooled from a high-temperature form, known as Austenite, to a low-temperature form, known as Martensite. The temperature at which an SMA remembers its high-temperature form is adjusted by slight changes in alloy composition and through heat treatment. In Nickel-Titanium alloys, the high-temperature form can be changed from above +100 degrees Celsius to below xe2x88x92100 degrees Celsius. The shape recovery process occurs over a range of just a few degrees. The start or finish of the phase transformation can be controlled to within a degree or two if necessary.
A coiled SMA may be used as an actuator, as represented in FIGS. 1a-1c. For example, FIG. 1a shows a coiled SMA tube 1 comprising a coil 4 between an input lead 2 and an output lead 3. The coil 4 is easily expanded lengthwise when the SMA is in its Martensite phase. The coil 4 reverts to its Austenite phase when heated by a hot fluid 5 therein and recovers its original shape with great force, as represented in FIG. 1b. The coil 4 may be cooled by a cold fluid 9, as represented in FIG. 1c, reverting the SMA to its Martensite phase so that it is again easily deformable.
Spring-shaped elements composed of shape memory alloys are described and claimed in two patents. However, the application of a coiled SMA tube 1 for the extension and retraction of telescopic wings as claimed by the present invention herein is neither described nor claimed in the related arts.
For example, Baumbick, U.S. Pat. No. 6,367,250, describes and claims a micro-actuator comprising a coiled wire composed of shape memory alloy communicating with and moving a flapper arm to adjust flow between a pair of jet pipes. The coiled wire is energized by optical energy.
In yet another example, Baumbick, U.S. Pat. No. 6,151,897, describes and claims a micro-actuator to adjust flow between a pair of jet pipes. The coiled wire is heated along its exterior by a hot gas from a gas turbine.
Therefore, what is currently required is a mechanically simple telescopic wing that minimizes the likelihood of mechanical failure during extension and retraction of wing segments.
What is required is a mechanically simple telescopic wing having an actuator activated via fluid and electrical means so as to provide redundant control capability over extension and retraction functionality.
What is require is a mechanically simple telescopic wing having a lightweight actuator that facilitates extension and retraction functionality between wing segments yet minimizes power requirements therefor.
An object of the present invention is a device capable of extending and/or retracting one or more wing segments in a telescopic fashion so as to minimize the likelihood of mechanical failure.
A further object of the present invention is a device capable of extending and/or retracting one or more wing segments in a telescopic fashion when activated via a heated fluid or electrical current.
A further object of the present invention is a device capable of extending and/or retracting one or more wing segments in a telescopic fashion while minimizing power requirements therefor.
The present invention is comprised of an inner wing segment, an outer wing segment, and an actuator. The inner wing segment is telescopically disposed from within the outer wing segment. The actuator is a coiled tube composed of a shape memory alloy. The actuator is fastened to one end of the outer wing segment and to the opposite end of the inner wing segment so that the actuator is disposed in a lengthwise fashion along the length of and within the telescopic wing system. The coiled tube contracts when heated thereby extending the inner wing segment from the outer wing.
Alternate embodiments of the present invention include a resilient element, one example being a mechanical spring, fastened at one end to the inner wing segment and the other end to the telescopic wing system. The described arrangement allows the resilient element to expand when the inner wing segment is extended thereby exerting a retraction force of lesser magnitude than the actuator. The resilient element retracts the inner wing segment when the coiled tube is cooled and the actuator force is removed.
The coiled tube may be heated by a fluid, including liquids and gases, and/or an electrical current directed through the coiled tube. It is likewise possible to cool the coiled tube via a fluid. The fluid may be vented after passing through the actuator in an open loop configuration or re-circulated in a closed-loop system, with or without feedback control.
Several advantages are offered by the present invention. The invention minimizes the number of moving elements within the telescopic wing system thereby simplifying design and function, increasing reliability, and minimizing cost. The invention minimizes power requirements. The invention provides greater power density and greater translational capability than comparable size electromechanical devices. The invention weighs substantially less than electromechanical devices with comparable performance. Furthermore, the invention is easily adapted to a variety of surface, air, and water craft.